In the late 1940s Kvale designed a wildcat called 8mm Kvale. It was intended for use in the German surplus 8mm Mauser M98 that flooded the American market after the war and was therefore nicknamed 'Poor Man's Magnum'. Kvale used the case from the .300 H&H Magnum and reduced the rim diameter so it would fit the bolt of a Mauser M98. The lessons learned from this cartridge were put into the .308 and .358 Norma Magnum.

Cases for the cartridge can be purchased from Norma or made in three ways: Necking up a 7 mm Remington Magnum case, necking down a .338 Winchester Magnum case, or running .300 Winchester Magnum cases through a full-length sizing die. Since the first two options leave the brass a bit short, the third is generally considered to be the best option. Ammunition for this caliber is not cheap (typically US$50–60 for 20 cartridges) and as such it is mainly of interest only to handloaders who own a rifle chambered in this caliber. The cartridge makes use of a belted case for headspacing.